Tag: biology

Cytokinin are a class of plant growth substance that promote cell division or cytokinesis in plant roots and shoots. They are involved primarily in cell growth and differentiation but also affects apical dominance, axillary bud growth and leaf sensecence. Pruning of plants promote branching because the axillary buds get sensitized to cytokinin.

Cytokinins promote cell division and differentiation of young, relatively unspecialized cells into mature, more specialized cells in intact plants. They are a required ingredient in any plant tissue culture medium and must be present for cells to divide. In tissue culture, cytokinins interact with auxin during the formation of plant organs such as roots and stems. For example, in tobacco tissue culture a high ratio of auxin to cytokinin induces root formation, whereas a low ratio of auxin to cytokinin induces shoot formation.

Cytokinins stimulate cell division, even in non-meristematic cells, in presence of auxin. They are most abundant in the growing tissues which are active site of cell division, for example: root, embryos, fruits etc. Coconut water is the liquid endosperm, the actively dividing tissue which serves as nutrition source for developing coconut embryo. Coconut water is used as growth promoter of developing embryos in tissue culture studies. It stimulates the growth of cultures of embryo due to presence of cytokinins. This makes option D correct. Abscisic acid (ABA) is a growth retardation hormone which inhibits seed germination and seedling growth. This makes option C incorrect as endosperm does not have growth retardation hormone. Option A is incorrect as auxin is the hormone of cell division and cell expansion, i.e., overall growth, while endosperm carries the hormone for cell division to increase the cell number only. Option B is incorrect as gibberellins are the hormone of stem elongation in genetic dwarf plants only.

In botany, kinins were the first name given for these phytohormones. It resulted in lot of confusion. Thus, it was later changed to cytokinins to avoid confusion. It was coined by Letham in 1963.

The cytokinin hormones promote cell division and tissue growth, and depend upon the presence of auxins to determine the extent of their activity. When the ratio of cytokinins to auxins is relatively high, stem and leaf growth is stimulated. 

Zeatin is a natural cytokinin first isolated from maize. It is an adenine derivative. The name zeatin was coined by Letham. It stimulates cell division or cytokinesis in plants.

Kinetin is a type of cytokinin, a plant hormone. It is involved in cell division. Chemically it is 6-furfuryl amino-purine. It stimulates growth and development in plant.

A 6-(4-Hydroxy-3 Methyl-trans-2-butenylamine) purine is a chemical name of trans zeatin. It is a type of cytokinin, plant hormone. It was first found in Zea maize. It stimulates the cell division process in plants. It acts as plant growth regulator.

Zeatin is a type of cytokinin, a plant hormone. It stimulates cell division. It is present in coconut milk. It was first isolated from Zea maize (corn kernels). It stimulates growth in plants. 

Cytokinin is a plant hormone that promotes cell division in root apex, shoot apex and young fruits. It is also involved in apical dominance and leaf senescence. They are not found in mature fruits.